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Power problem or motherboard

I am workng on a computer that has a power problem. The owner told me that it was working fine the other night and he shut it down and when he went to start it the morning all he would get is a momentary light on the cd and nothing. I hooked up a known good power supply and when I turned it on all that would happen is a 2 second spin on the cpu fan and the case fan. I changed the switch and no change. I will often will get the same spin when just plugging in the power supply which I have seen before and believe that is normal??. If I use the switch I will get the short fan spin but will not spin again until I unplug the power supply and let it rest a short while plug it back in and then 1 spin with 1 click of the switch with nothing if I hit the switch again. Unplug the PS and I will get 1 short spin again.

I started by unhooking power from the cd , hdd, floppy, case fan (which will also spin for 2 seconds), and the sound card wire. No change. I changed the cpu fan and still no change. At this point I have the mobo on my workbench with just a PS , switch, cpu fan and a stick of ram which I also changed out for a new one.

Am I missing something? the guy keeps calling for and update.

 Mobo is an ECS K7s5a ver3.PC is a clone. PS is a TigerPro TP300, Memory is SD 2700 (512)
 I don't know the cpu speed but it will take a 1.4 Amd athlon and he did say he had someone upgrage his computer a short while back so I am assuming it is probably the max.

Anything else you guys can think of?

Thanks, dmcalert.
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dmcalert
Asked:
dmcalert
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2 Solutions
 
newuser4Commented:
I had the same problem with an Xp 2400+, the heat spreader was not mounted correctly and the internal thermal sensor was shutting it off when the motherboard received power. The same problem can be caused by failing tachimetric sensor in cpu fan.

You have to check heat spreader, use the thermal paste to ensure contact between cpu core and spreader base (clean old thermal pad traces), then reset the cmos to clear the error and try turnig it on.
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al-hasanCommented:
dmcalert: what happens if you take the RAM completely out? The board should beep more or less wildly then, if it is okay.

Regards,
has.
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maimon22Commented:
you need to check the hard drive connector first to make sure the ide cable isn't lose on both ends.
and you need to check if the cpu fan is working and all others also and look at the motherboard manual for hookup instructions they might not all be right
if not follow these Steps:  
1.   If your desktop computer does nothing at all when you try to start it, first check that the power cable is securely plugged in at the back of the computer as well as into a working power outlet. It's amazing how often this is the case.  
 
2.   If you're starting from a button on the keyboard, make sure the keyboard is connected to the computer.  
 
3.   If the computer is plugged into a surge protector, see if the surge protector has a reset switch that you can push. (If it doesn't have a reset switch and the problem is with the surge protector, it will need to be replaced.) Try plugging a lamp or other device into one of the surge protector's outlets to make sure it's working.  
 
4.   If you can hear the computer's fan or hard-disk drive, or if you can see indicator lights on the main unit but the monitor stays dark, make sure that the monitor is connected to a working power source, that it's turned on and that it's securely connected to the computer via the video cable.  
 
5.   If the monitor and computer have power but the computer displays a "Non-system disk or disk error" message, check to make sure you didn't leave a disk in the A: drive. If you did, eject it and restart the computer.  

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maimon22Commented:
if you have done all of these steps carefuly then  When the fan starts, but nothing else does, the power supply unit may need to be replaced.
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DRZCMCommented:
I might actually be the microprocessor.  Test it on another board to identify wether it is the board or the microproccessor.  I have had this problem on older AMDs and it is usually one or the other.

Dr. Z
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WatzmanCommented:
I think it's the motherboard or CPU (more likely the motherboard).  The motherboard has a switching power supply on it that supplies Vcore to the CPU, it's usually driven by the 12 volts rail of the power supply.  A short in that power supply (the one on the motherboard) will cause the symptoms that you are describing.

[It's evident that many of the other responders did not really read you post and what you have already done.]
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willcompCommented:
I agree with Watzman that it is most likely the motherboard.  Many socket A motherboards that max out at 1.4 GHz CPUs were manufactured during the "bad capacitor (cap)" period and symptoms you describe are often asscociated with failed caps.

Take a look at the caps and see if any have bulging tops (top should be flat) or signs of electrolyte leakage.  If so, motherboard has failed and must be replaced.  Some manufacturers will replace/repair under an extended warranty.

You have already stripped down to bare essentials (good practice when troubleshooting) and replaced power supply and RAM.  So basically, only CPU and mobo are left to deal with.

Dalton
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dmcalertAuthor Commented:
I did decide to check out the cpu. I have remove a few heatsinks and I could not believe the pressure to release the clip from the open side. I was able to release it only to see why it was so hard. The person who upgraded the cpu put the heatsink on backwards and crushed the corner of the die . I have nothing to lose , so I cleaned it off and will put some paste on it and put it in one of my test machines.Watzman, I agree with you that it is the onboard SWPS is the problem. . I was aware of it's importance (the box power supply is really just a dumb power converter).I wanted to see if someone else would verify what I feared. i have heard to many other techs say " replace the mobo". I work with them every day and I dislike just being a part replacer. I was afaraid I would have to give the owner the bad news but he was talking about upgrading the whole thing anyway so now will be the time. I think I have the answers I need but I will leave this open this evening and finalize. If you have anymore insight please add.  I will let you know on the cpu. Curious to see how much stress it can take.

thanks, dmcalert
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dmcalertAuthor Commented:
I eliminated the cpu as I put a good one from a test macine in it and it made no difference.  willcomp, There is was in front of my face. There were 2 caps bulging with the tops splittting and brown stuff starting to come out. Would you and Watzman
mind splitting points. I will give Watzman the accept for confirming what I had thought and an assist to you for your great added insight into the problem and another good hardware lesson that I'm sure I will use again and again.

Will wait to hear
dmcalert

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WatzmanCommented:

The caps are in the switching power supply (the one on the motherboard that supplies the CPU Vcore).  About 2-3 years ago, there was a rash of defective electrolytic caps made in taiwan, the culrprit was a going-bankrupt chemical company that intentionally left out an expensive ingredient from electrolyte used by capacitor makers.  Several hundred bad caps were made.  Congratulations, you won (lost?) the "bad cap lottery".  [Note, the motherboard might be covered by the mfgr. even though the warranty has nominally expired.  Also, replacing the caps is relatively easy and may fix the problem.]

Anyway, that is the problem, and "gets to the bottom of this".
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WatzmanCommented:
Make that several hundred million bad caps were made.
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willcompCommented:
Actually there were probably millions of those caps sold.  Of mobo brands that I've seen, only Intel manufactured boards have not had any.  Have seen them on MSI, Gigabyte, FIC, Asus, Soyo, and Abit boards.

Electrolyte formula was stolen in a case of industrial espionage.  Only problem was that formula was incomplete.  So electrolyte and caps manufactured by culprit company were faulty.  They sold for less and were used extensively since mobo manufacturers need to cut costs to stay competitive.

They are mainly on motherboards that are now about 3 to 5 years old and any manufacturer except Intel is suspect.  Note that Intel chipset mobos from other manufacturers are susceptible.

I'm not points driven, so go ahead and split.  Watzman was much closer to the right track that previous responders.

Replacing the caps may be easy for someone with excellent soldering skills, but that eliminates me.

Dalton
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willcompCommented:
Watzman,

By the time I got through typing the above (several interruptions) you got the millions part in.

Dalton
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dmcalertAuthor Commented:
Sorry I did it wrong again (spliting points) Will the moderator please split points: 300 pts for Watzman and 200 pts for willcomp.

Thanks,
dmcalert
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dmcalertAuthor Commented:
I think I am suppose to ask this in community support but I can't find the question #. Are you still using Q#s?. Please advise
thanks again
dmcalert
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